Solar panel fires!

[max2k]

Unlike most consumer equipment, solar runs quite high power, using facilities not too far
from capacity, for long hours, cycling every day, with no one watching. I think that raises
the chances of a fault a huge amount, with more serious consequences.

I do run a welder, a car lift, some multi horse electric motors. But those have an extremely
light duty cycle, and I am generally right there at the time. The huge majority of my house
wiring is just sitting there for my convenience, doing next to nothing all the time. Bruce Roe

My point was simple- solar does not bring extra danger compare to any other equipment. Mistakes happen everywhere and yes, it's an additional component but following this logic we should use candles. Oh sorry, fire hazard again . Some of the equipment you listed is probably more dangerous than solar, you just get used to it.

[SunEagle]

My point was simple- solar does not bring extra danger compare to any other equipment. Mistakes happen everywhere and yes, it's an additional component but following this logic we should use candles. Oh sorry, fire hazard again . Some of the equipment you listed is probably more dangerous than solar, you just get used to it.

We are not saying to stay away from a solar pv system because they are dangerous. We are saying that due to their nature of being outside (wind & water intrusion) and with the possibility of being installed by less than professional people will increase the chances of a fire being started from an electrical issue.

Nothing is perfectly safe. Just how and where something is installed can change the potential % of a failure.

[DanS26]

That was one of the first things I thought about, and one of many reasons I have a ground
mounted array hundreds of feet from any building. I am going to add this which just might
relate to some fires.

After some 22 months of service, I have decided to join the "TIGHTEN ALL CONNECTIONS
REGULARLY" school. I have been running 15 KW out every sunny day not just at solar noon,
but for many of the daylight hours. None of the wiring is approaching its absolute limit,
but at the end of sun it can definitely be felt to be warmer than the surroundings.

There are a couple inverters, DC and AC disconnect boxes, several AC breaker boxes, and a
DC combiner box. All the connections were initially checked by me. About a year ago a
circuit breaker failed, apparently from heat at one of the line terminals. This month a DC
screw connection to a disconnect switch (carrying 21A @ 360 VDC) burned out. The
problem was detected & repaired in a couple hours, but the issue is, why did it happen
at all?

As others have suggested, perhaps the constant heat/cool cycles at significant power can
work these connections loose. Loose enough, the resistance will rise and they burn out.
I undertook (in the dark of course) to check them ALL for tightness. Sure enough, the
tightness of screws after 1.5 years varied A LOT. Since all were done by the same person,
often many the same day, some had apparently loosened up. My conclusion is that
these all need to be rechecked annually, at least until they ALL show some settling to
stability.

So far, no issues with split bolt or soldered connections. Bruce Roe

Bruce, did you torque all connections to specifications?

Torque screwdriver or wrench is an electrician's best tool but sadly hardly anyone uses them.

[bcroe]

Bruce, did you torque all connections to specifications?

Torque screwdriver or wrench is an electrician's best tool but sadly hardly anyone uses them.

I didn't use a torque wrench for this project. I certainly endorse them if available along with
the required torque specs and a qualified operator. They get used here on critical items like
engine assembly.

However, some of us who have been assembling things at home & work for 5 or 6 decades
have gotten quite able to detect the border between "pretty tight" and "in danger of stripping"
with a good right arm. The electrical stuff I put together was far more uniformly tight initially,
than when I checked it after a few seasons. Bruce Roe

[bcroe]

My point was simple- solar does not bring extra danger compare to any other equipment. Mistakes happen everywhere and yes, it's an additional component but following this logic we should use candles. Oh sorry, fire hazard again . Some of the equipment you listed is probably more dangerous than solar, you just get used to it.

You completely glossed over MY point. All that stuff is dangerous too, but the total running time
is on the order of a dozen hours a year. The total risk is MULTIPLIED by the number of hours in
operation, THOUSANDS of hours for solar. AND secondarily, my stuff is closely supervised against
fire risk; solar practically never is.

Candles, give me a break. Bruce Roe

[sensij]

You completely glossed over MY point. All that stuff is dangerous too, but the total running time
is on the order of a dozen hours a year. The total risk is MULTIPLIED by the number of hours in
operation, THOUSANDS of hours for solar. AND secondarily, my stuff is closely supervised against
fire risk; solar practically never is.

Candles, give me a break. Bruce Roe

I lump EV charging into this too, although there is probably less that can go wrong. Cars can charge at 6.6 kW, in the middle of the night when cold terminations will rapidly heat up... seems like higher risk than your average appliance.

[Sunking]

I lump EV charging into this too, although there is probably less that can go wrong. Cars can charge at 6.6 kW, in the middle of the night when cold terminations will rapidly heat up... seems like higher risk than your average appliance.

Already been multiple EV fires while charging. Neil Young burnt down his garage and part of his house. Over a million in damage. Added a new meaning to Crosses Burning justice.

[DanS26]

I didn't use a torque wrench for this project. I certainly endorse them if available along with
the required torque specs and a qualified operator. They get used here on critical items like
engine assembly.

However, some of us who have been assembling things at home & work for 5 or 6 decades
have gotten quite able to detect the border between "pretty tight" and "in danger of stripping"
with a good right arm. The electrical stuff I put together was far more uniformly tight initially,
than when I checked it after a few seasons. Bruce Roe

I read a study done with electricians on how well they could "feel" the right torque. I searched but could not find it, but what I remember is that the vast majority under-torgued and some over-torqued. The bottom line was very few hit the proper torque. This study was done with very experienced electricians.

Maybe someone could find it and post. I'd like to read it again.

[DanS26]

I read a study done with electricians on how well they could "feel" the right torque. I searched but could not find it, but what I remember is that the vast majority under-torgued and some over-torqued. The bottom line was very few hit the proper torque. This study was done with very experienced electricians.

Maybe someone could find it and post. I'd like to read it again.

Ahh.....Found it:

http://ecmweb.com/contractor/do-you-have-calibrated-arm

[inetdog]

Ahh.....Found it:

http://ecmweb.com/contractor/do-you-have-calibrated-arm

Very interesting, thank you!
A second question that would be interesting to ask electricians specifically is "what is the proper torque value for this component?"
A torque driver is of no particular benefit if you do not know what value you are trying for.

[SunEagle]

Ahh.....Found it:

http://ecmweb.com/contractor/do-you-have-calibrated-arm

You forgot to mention that most industries don't provide a large tool budget for their electricians to purchase a torque wrench.

Contractors like to work fast and use what ever tool is in their belt. Mostly a big screwdriver.

Maintenance electricians are more concerned with getting Electrically Insulated hand tools to prevent a shock or electrocution. Not everyone can perform the work de-energized.

[sensij]

Ahh.....Found it:

http://ecmweb.com/contractor/do-you-have-calibrated-arm

Neat data, although 2/0 connections are pretty serious. I would hope that the accuracy is better on the conductors normally used in residential PV systems... say, 6 to 10 AWG, but have no idea if that is true.

[Sunking]

You forgot to mention that most industries don't provide a large tool budget for their electricians to purchase a torque wrench.

Most all Electricians are self employed contractors. Your typical Solar Contractor is not even an Electrical Contractor or knows much about electrical. It is a General Contractor, Home Improvement, Roofing Contractor, and some EC's milking the market with the free money as a side job until the bubble bust next year. They in turn hire roofers and an EC to do the work on Sub Contract basis. Solar City is a Prime Example.

[DanS26]

You forgot to mention that most industries don't provide a large tool budget for their electricians to purchase a torque wrench.

Contractors like to work fast and use what ever tool is in their belt. Mostly a big screwdriver.

Maintenance electricians are more concerned with getting Electrically Insulated hand tools to prevent a shock or electrocution. Not everyone can perform the work de-energized.

Well, apparently that is penny wise and pound foolish. If 90% of electrical failures are caused by improper connections, those industries that do not provide the proper tools are just foolish and some would say dangerous.

The NEC and manufacturers provide the torque specs and it would be wise to comply.

[Sunking]

Well, apparently that is penny wise and pound foolish. If 90% of electrical failures are caused by improper connections, those industries that do not provide the proper tools are just foolish and some would say dangerous.

They are called self employed contractors. Just about all electrical shops require employees to provide their own tools.

Yes most electrical fires are from poor connections. Connections cover a wider area than you think. A switch and relay are connectors with connection terminals.